Relationships and races

In talking with my long distance-girlfriend, we often use the phrase "finish line" to set out a goal to keep ourselves happy and looking forward to seeing each other, and it got me thinking about this phrase, and how relationships as a whole don't really have a finish line.

Different people have different goals as couples/triples/octets etc, so for everyone it's different, but as a whole, I see a relationship as a long, endurance race with your partner(s). You meet up and start running, each lap a different stage of your relationship, whether moving in, getting engaged, getting a puppy; whatever goal is currently being worked toward. Sometimes someone falls back or lets go, and ends up with the runners needing to start the race over again with a new partner, maybe this time with different goals. 

In the end relationships in life are just seeing how far you want to run with each person, and whether you can make it another lap. Sometimes you may fall over and they can help, sometimes you find a new running mate and start over. 

Now I think about it, it's a bit grim how this implies the "true" end is when someone keels over and dies.